1: electricity fundamentals

Section 1: Foundational Physics - 1: Electricity Fundamentals

Electricity powers our world, from tiny gadgets to massive machines. At its heart, it's about the movement of tiny particles called electrons. Think of electrons as incredibly small, negatively charged building blocks of atoms. When these electrons move in a coordinated way through a material (like a wire), we get an electric current.

Imagine a simple circuit with a battery, a wire, and a light bulb:

1. Voltage (Volts - $V$): This is the electrical "push" or pressure provided by the battery. It's the force that motivates electrons to move. Think of it like water pressure in a hose. A higher voltage battery (like 9V vs 1.5V) provides a stronger push. It's the potential energy difference between two points.
2. Current (Amperes or Amps - $I$): This is the actual flow of electrons themselves through the wire. It's the rate at which charge moves. Using the water analogy, current is how much water (electrons) flows past a point in the hose (wire) every second. More current means more electrons moving per second.
3. Resistance (Ohms - $Ω$): This is how much a material opposes or resists the flow of electrons. The wire has some resistance, but the filament inside the light bulb has much higher resistance. This resistance is what causes the filament to heat up and glow, producing light. Think of it like a kink in the hose restricting water flow. Materials like copper have low resistance (good conductors), while rubber has very high resistance (an insulator).

These three concepts are beautifully linked by Ohm's Law:
$V = I \times R$

• If you increase the voltage (push), the current (flow) increases (assuming resistance stays the same).
• If you increase the resistance (restriction), the current decreases (assuming voltage stays the same).

Finally, Power (Watts - $W$) tells us the rate at which electrical energy is used or converted into other forms (like light or heat). It's calculated simply as:
$P = V \times I$
The light bulb converts electrical power (from the battery) into light and heat power. A higher-wattage bulb uses more electrical energy per second.

Understanding these core ideas – electrons, voltage, current, resistance, Ohm's Law, and power – is the essential foundation for exploring everything else in electronics. They are the basic language we use to describe how electrical circuits behave.